2 Answers
2

The general approach to gaining "root" on the HTC Incredible 2 is to get S-OFF, so you can flash a custom ROM. I'm on the road now, and have neither the inclination nor the resources to compose a full guide here, so I will point you to the best rooting guide for our phone:

Note: the guide is aimed at Linux users--use an Ubuntu live CD if you have to.

Anyway, it's a much better guide than the ones I see in the Google top 10, which are either hard to follow along, or leave out (possibly) necessary steps, like hboot downgrading. Finally, another helpful resource:

If you like to learn visually and would rather not go through of steps, check out this YouTube video.

Some warnings:

This is not a FULL unlock (S-OFF or to unlock your SIM card slot.)
This WILL VOID your warranty.
This will work with ANY version of HBOOT.
-This is a how to for WINDOWS ONLY.

If you are logged out of HTC Dev at any time during the identifier period (1 - 5), just sign back in and don't click anything. It will automatically redirect you to the last page you were on.
I am not responsible if you didn't follow a step correctly and your phone lights on fire, cracks into two, wants to destroy you, etc...

What you are going to need:
-A computer
-Fastboot and ADB [API] <-- These are applications to be use to flash ROM's.
-HTC Drivers <-- Drivers HTC gives, couldn't find them on HTC's site.
-Android SDK
-microUSB cable, phone, and some time

STEPS TO ROOT:

1.) You are going to want to head over to the HTC Dev[eloper] site ([link]) and make an account or sign in. Once you have done one of the two, you are going to want to click 'Unlock Bootloader,' then 'Get Started.' It will next ask you what device you are trying to unlock, click 'Droid Incredible 2 (Verizon)' then 'Begin Unlock Bootloader.' Then a pop up window will ask you if you are sure, just click 'Yes.' Then, another pop up window will appear, just tick the two boxes and press 'Proceed to Unlock Instructions.'

2.) Go to your phone. Take off the [back] battery door and remove the battery (don't hold the power button and make it a proper shut off, just rip the battery out. Then, put the battery back in. Once you have replaced the battery, hold the volume down button and the power button at the same time until a white screen shows up. You can use the volume rocker to highlight your selection, and the power button to select the highlighted selection. Right now, we want to highlight 'BOOTLOADER' and use the power button to select it. Next, grab your miniUSB cable and plug it into your computer to your phone.

3.) Next, make a folder on your computer in the C:\ Drive. In Windows Vista & 7, you can just go to Computer from the Start Menu and it will be labeled Local Disk (C:). You can name the folder whatever you want, I am just going to name it Android. Next, you are going to want to download my ADB, Fastboot, and ADBAPI .zip file and place all three files into the Android folder. After you unzip the ADB/Fastboot folder, you are going to want to (if you have not already) download and install the Android SDK manager. You will need to install SDK tools [and I believe a version of Android?] After you have installed everything, you can go to the Start Menu again and type in 'cmd' in the search bar and press enter. Then type in the following: (Or you could take the easy way of going to your C:\ drive and shift-clicking the folder and press 'Open Command Window Here...)
Code:

cd C:\Android

4.) After you have got into Command Prompt and are in the \Android folder, type in the following:
Code:

fastboot oem get_identifier_token

You will then see a great big brick of random characters. Right click in the bottom right-hand corner of '<<<<< Identifier Token End >>>>>' and click 'Mark...' Hold down the left-mouse-button and select the great brick of text up until '<<<< Identifier Token Start >>>>' (don't highlight any of the 'INFO' things.) Then, right-click again and you will have the identifier token copied to your clipboard. Back on the HTC Dev site, it will ask you for your identifier; just paste the identifier in the box and it will send you an email with a .bin file (Unlock_code.bin) and just throw that into the folder with ADB and Fastboot.

5.) You are going to want to click the continue link that HTC Dev sent you as well to downloading the file. After you have finished downloading and put it in the folder, type in the following:
Code:

fastboot flash unlocktoken Unlock_code.bin

Once you have done that and pressed Enter, your phone will change screens. It will ask you if you are SURE you want to do this. Just press the volume rocker up and press the power button. Your phone will reboot and take you back to Android. It's normal and it doesn't mean it failed... Your phone is fine and it should have went OK if you followed the steps. We are done with HTC Dev now, so you can close it.

6.) Next thing we are going to want to do is flash ClockWorkMod (CWM) Recovery onto your phone. You are going to want to download the .iso for CWMR and flash it to your phone (download link [link].) After you are done downloading the .iso, place it into your ADB and Fastboot folder. Once your phone has finished starting up, take the battery out again and put it back into HBOOT mode (step 2.) You are going to want to go back into FASTBOOT (step 2, again) and flash the recovery by doing the following:
Code:
fastboot flash recovery recovery(press TAB)
Once you press enter and fastboot says it has completed, it will just have the Fastboot screen. Just highlight 'Bootloader' and press the power button. Next, to make sure it worked... Scroll down to 'Recovery' (which is right under Fastboot) and select it. The HTC screen should show and then CWMR should come to life.

7.) This is where the real magic happens. We are going to install SuperUser on to your phone now. Reboot your phone into regular Android. Now, you can plug it into the computer and make it a disk drive or pop out the miniSD card and put it into a converter. Now, you are going to want to download SuperUser ([link]) and put it onto the miniSD (I recommend not putting it in any folders so it is easy to find.) Now, put your phone back into CWMR (step 6.) Now, use the volume rocker to scroll down to 'install .zip from sd card' and press the power button. Now, find the SuperUser.zip (or whatever it is named) and press the power button. The 'yes' to install it is in the middle of all the 'no' options, use the volume rocker to select 'yes' and press the power button. Wait for CWMR to finish, and in the meantime... Just stare at your phone. After you have finished installing SuperUser, restart your handset into Android. Once it has finished restarting, go into the app drawer and find the SuperUser app. Press the 'menu' button and tap 'Settings.' Scroll down to 'Su Binary x.x.xx' and tap it. On the bottom it will say 'Update Binary,' just tap that and it will do its 'magic.' Once SU has finished updating Binary, you have a rooted DINC2.